EXECUTIVE SUMMARY
Electronic waste ('e-waste') is becoming an increasing environmental
concern. With faster devices replacing older or obsolete items, increasing
amounts of electronic waste are being sent for final disposal in Canada.
A recent study commissioned by Environment Canada indicated that e-waste
is known to contain various inherently hazardous substances, including
mercury, cadmium, lead, and beryllium, which, if improperly managed (i.e.,
during e-waste processing) may pose significant human and environmental
health effects.
In Canada, the electronics recycling ('e-waste recycling') industry,
whose main purpose is to manage and dispose of the growing quantity and
hazardous content of e-waste is generally considered to be a fast growing
and rapidly evolving industry. The industry, although considered to be
in its infancy, includes well over one-hundred different e-waste recycling
facilities operating throughout Canada. In general, the industry is anchored
by several large, state of the art recycling and processing facilities
and many other small to medium sized operations which may use a variety
of techniques and methods to separate and process e- waste.
In general, several issues have been identified with the processing and
recycling of e-waste since this waste stream contains a number of heavy
metals and other substance that, if managed improperly, and depending
on the level of exposure could be potentially hazardous to both human
health and the environment.
MJC & Associates ('MJC') were retained by Environment Canada and
Industry Canada to conduct screening-level human health and ecological
risk assessments (SLHHRA and SLERA) for a 'generic' e-waste processing
facility to assess 'generic' waste flow processes. A generic facility
is conceptual. It is meant to summarize the general features or characteristics
of a typical e-waste processing facility in Canada. The use of a 'generic'
facility and process was necessitated as there are many e-waste processing
sites in operation in Canada using a variety of operational technologies,
from small scale operations to more large-scale 'state of the art', well
resourced facilities which employ a range of processing technologies.
The risk assessment was conducted by applying an assessment framework
to a 'generic e-waste facility' and 'waste- flow process', and included
the formal identification of receptors of concern (both human health and
ecological), in addition to identifying relevant exposure scenarios and
exposure pathways for these receptors.
The general approach for the human health and ecological SLRA's were
based, in part on the risk assessment frameworks provided by Health Canada
and others (i.e., CCME, MOE, EPA, etc.) but tailored to address generic
e-waste facilities and the unique consideration and reality that limited
data (e.g., environmental monitoring data of air, soil, water, from or
at these facilities etc.) were available for assessment.
Part A
Occupational Hazard Assessment
The principal findings of the occupational and human health risk assessments
can be summarized as follows:
- An area of significant concern is the establishment of recycling
facilities which are low- budget operations lacking resources to adequately
equip the facilities to mitigate workplace hazards or to properly train
their staff. The operational focus of such facilities should be limited
to operations such as disassembly of equipment that will not result
in exposure levels likely to cause harm. Such operations can still operate
with minimum hazard to workers if they are able to form partnerships
and/ or associations with other companies that have appropriately trained
personnel to operate equipment to recycle the electronic waste produced
by such operations. As an example, a piece of equipment called a shredder
is very expensive to purchase and operate and smaller companies would
be better served if they sent disassembled (and sorted) components to
a larger facility that operates this equipment on a routine basis.
It is our opinion that training programs provided by the facility to
the workers are the best means of mitigating risk in the absence of removing
the hazardous process or preventing worker access to a hazardous aspect
of the process.
It is our recommendation that training programs be developed for each
of the waste flow processes taking place at a facility. The conceptual
model provided in this document provides a framework on which the training
programs may be based (however, the proper design of training programs
is beyond the scope of this document.) This approach is preferred over
a generic training program because of the diversity of the occupational
risks associated with the different processes. In addition to training
programs, the facility design could prevent worker access to hazardous
processes and situations as dictated by a "Hierarchy of Controls"1
approach to e-waste processing. This is generally addressed by individuals
designing the e-waste facility.
Lastly, the formation of an industry-government group to specifically
deal with electronic waste recycling issues in the context of occupational
and environmental health is recommended. The mandate of this group would
be to promote programs within recycling facilities to ensure worker safety
and environmental stewardship (e.g., industry codes of practice and environmental
management standards). Worker safety programs would deal with occupational
and human health issues while the environmental stewardship programs could
promote associations between smaller and larger recycling facilities.
The group would also oversee the design and upkeep of the training programs
as well as their delivery by establishing training and workplace standards.
In addition, it may be easier for a joint group to approach electronic
manufacturers to discuss product stewardship as well as obtain expertise
to design training programs.
Following the development of a generic facility and e-waste flow process
model, and a review of the occupational hazards associated with typical
e-waste facilities, a 'Screening Level Human Health Risk Assessment' ('SLHHRA')
was conducted to assess the human health hazards associated with the processing
of electronic waste and exposure to several chemicals of concern.
With respect to the chemical hazards associated with e-waste facilities,
the principal findings can be summarized as follows:
- Exposure to the metals and chemicals of concern can occur throughout
the e-waste processing cycle, including processes related to shredding,
sorting, packaging, etc. and as a result of exposure to various media
(e.g., air, dust, soil, etc.) through direct contact exposure pathways.
- Derived generic, e-waste specific exposure limits were ranked in
terms of potential to cause human health toxicity from greatest to lowest,
indicating that chromium > beryllium > nickel > cadmium >
arsenic > azo-colourants > phthalate, following exposure of a
female receptor of concern at a typical e-waste facility. This ranking
is considered to be useful to identify chemicals or classes of chemicals
for which practical mitigative measures could be developed to reduce
and manage potential exposures. In addition, the exposure limits could
be used in higher tiers of assessment, including site-specific risk
assessments to 'screen' out potential chemicals and focus attention
on those considered to be the most important.
- From the ranking, the metals and other compounds which can exist
in particulate form and to which human receptors could be exposed to
through the inhalation exposure pathway are considered to pose significant
risks to human health for a generic e-waste facility. Therefore, to
reduce the exposure of workers and others to these metals, personal
protective clothing, including use of proper dust masks, gloves, and
other protective gear (coveralls, boots, etc.) is considered to be a
practical risk mitigation technique.
- A further chemical specific screening-level assessment was conducted
for lead, a hazardous metal using the U.S. Environmental Protection
Agency's Adult Lead Methodology (ALM) model. The model assumed that
an adult female was exposed to an upper-bound maximum concentration
of 1000 µg/g of lead in dust. The results indicated that there
would be a 6.5% probability that the target blood-lead screening level
of 10 µg/dL for the fetal blood lead level would be exceeded.
This exposure level would be considered to present an unacceptable hazard
to the fetus and to pregnant female adult workers exposed to lead in
dust at these concentrations while working at an e-waste recycling facility.
- Overall, there is little available empirical data to evaluate the
potential risks associated with residents being exposed to various chemicals
of concern from living in proximity to an e-waste processing facility.
Therefore, it is recommended that further environmental monitoring,
such as stack and effluent testing, groundwater/drinking water monitoring
and soil sampling in close proximity to these facilities be undertaken
to reduce the uncertainties in the above findings.
- Likewise, there is a paucity of data concerning the concentrations
of the identified chemicals of concern anticipated to be found within
the work environment of an e-waste facility. Examining the data that
were available concerning the concentrations of several metals within
the work environment of e-waste facilities, it was concluded that, at
the screening-level, workers may be at risk, as the levels of several
metals, including lead and beryllium were found to be above the occupational
exposure limits identified by the ACGIH.
- Further research addressing the potential for occupational exposure
to CoCs within e- waste recycling facilities is recommended as an area
of priority. To attempt to bridge this data gap and provide a means
of quickly assessing the risks posed to e-waste workers, generic exposure
limit criteria or screening level values were developed for a number
of the CoCs.
- Given the differences in terms of operational capacity, and potential
variety of e-waste processing methodologies currently available to recycle
e-waste, it is recommended that individual e-waste facilities develop
and complete, as a pro-active approach "potential problem analysis"
or "failure model analysis" assessments or other suitable
approach (e.g., Canadian Standards Association 'Standard CAN/CSA-Z731-03'
methodology) for their facility operations (infrastructure, socioeconomic,
processes, etc.). This would aid in identifying those components of
an operation which, if a failure mode or catastrophic event were to
occur (e.g., failure of a bag-house, shredding of an ink cartridge,
etc.), could potentially result in a significant and unacceptable human
health or ecological event. This proactive approach is employed and
very common to other industries, such as the mining and chemical sector.
- E-waste facilities should initiate and conduct pro-active approaches
to systematically manage their environmental and occupational health
and safety risks. Management systems (e.g., ISO 14001 and British Standards)
provide structured approaches and processes for the achievement of improved
environmental and safety performance.
- Given the evolving nature of the e-waste recycling and processing
business in Canada, legislative requirements are one of several possible
approaches to addressing the risks associated with e-waste processing.
Further risk characterization, and enhanced environmental monitoring
is necessary to determine if mandatory (i.e., legislative) or voluntary
(ISO-based etc.) approaches are appropriate.
Part B
Screening Level Ecological Risk Assessment
A Screening Level Ecological Risk Assessment (SLERA) was conducted to
assess the risk to the natural environment from processing electronic
waste. For this component of the study, a 'generic facility' was defined,
in order to allow analysis of exposure pathways and receptors based on
a generalized concept of a typical environment where an electronics recycling
plant might be located. Levels of chemicals of concern used in the risk
assessment were taken from the very limited analyses of media (i.e., air,
soil and dust) from e-waste processing plants where information was available.
However, there is a significant level of uncertainty in the screening-level
assessment as a result of the lack of available data.
For the purposes of a screening-level assessment, the generic facility
was considered to be at the interface between the urban and agricultural
landscape. Abandoned agricultural fields, hedgerows and small patches
of woods would likely be in close proximity to the facility. Small drainage
ditches or small creeks, connecting with larger creeks or wetlands downstream,
may be found nearby. The native wildlife that uses these patches would
mainly include those most familiar to urban residents, including mammals
such as deer mice, short-tailed shrews, raccoons, skunks, foxes, birds
such as blue jays and northern cardinals, reptiles such as garter snakes
and amphibians such as toads and leopard frogs. However, it was assumed
there could be significant species in the vicinity, for example, Red-shouldered
Hawk, defined by the Committee on the Status of Wildlife in Canada (COSEWIC)
as a Species of Special Concern, occasionally inhabits larger patches
of forest in agricultural landscapes. The shorter list of Valued Ecosystem
Components (VECs) were selected to represent those with a key role in
wetland and upland ecosystems, as well as significant species.
There are three potential pathways by which chemicals of concern could
enter the generic natural environment from processing electronic waste.
The most important pathway is dispersal of dust from the shredding process,
from the plant to the environment through doors, ventilation systems,
etc., where it could become deposited in the soils and wetland sediments
outside the plant and then ingested or absorbed by VECs. A second pathway
would result if water were used in any part of the process, especially
if dust were not controlled, and drains allowed the water to migrate from
the site into soils and sediments. A third pathway would result if electronic
components were stored outdoors before being disassembled. In this case,
water could leach through and drain into the local watershed, carrying
with it dissolved chemicals of concern that would then be deposited in
soils or water. Leachate could also percolate through the ground and contaminate
groundwater. Inhalation pathways are not likely to be significant, as
dust in the air outside the plant would be dispersed by wind currents
or deposited over long ranges.
The risk assessment was limited to those chemicals that were reported
to be of most concern, considering the limited information available for
e-waste. Lead is the substance of most concern, as it has the highest
potential for leaching from electronic waste. However, there are known
to be high proportions of cadmium, mercury, beryllium and polybrominated
diphenyl ethers (PBDEs) in electronic waste.
This assessment shows there could be significant exposure of all trophic
levels from processing electronic waste if contaminated dust is able to
migrate outside the plant in air or water and become deposited in soils,
sediments, surface water and ground water, and then is ingested directly
by organisms in the environment. Water could possibly also become contaminated
if recycled components were stored outdoors allowing rainwater to leach
through the e-waste. However, the extent to which chemicals actually migrate
into the environment through these mechanisms is not known.
The risk of toxicological effects from heavy metals could be highest
for organisms that directly ingest or allow uptake of dust, including
plants, amphibians, and burrowing mammals that ingest earthworms (since
earthworms tend to contain soil in their gut). Risk of toxicological effects
from heavy metals, particularly lead, is also likely to be high from exposure
of organisms at a higher trophic level to plants or invertebrates that
are exposed to dust on the site, as uptake rates for heavy metals in plants
and invertebrates can, in some cases be very high. However, there is a
high degree of uncertainty associated with this statement.
There are several factors contributing to the high degree of uncertainty
associated with assessment of risk at the generic site. The most important
factors are:
- there are almost no empirical measurements of concentrations of contaminants
of concern in the vicinity of electronic waste processing sites in North
America;
- the levels of contamination in dust are likely to be highly variable
depending on the type of waste accepted by the recycling facility;
- levels of contaminants in soil, sediments and water outside a plant
are likely to vary because of varying environmental practices, with
some likely having negligible emissions;
- contaminants in dust may have variable bioavailability, depending
on the other components in dust and leachate and the environment in
which they are deposited;
- it is not known whether contaminants can move from dust to soil,
sediments or water, or what form they may be found in those media;
- accurate benchmarks for some contaminants, most notably beryllium
and PBDE, have not been derived.
Because of this uncertainty, it is recommended that a further tier of
risk assessment be undertaken, which should include:
- measurement and characterization of metals and PBDEs in soils and
aquatic sediments in the vicinity of electronic waste recycling plants.
The sampling should be large enough to encompass an array of plants
with a variety of environmental practices, and should be especially
focused in areas most likely to be contaminated by dust in air or drainage
water: in front of loading doors, near ventilation systems, near drain
outfalls, and at points of groundwater discharge;
- bioassays should be conducted on uptake of contaminants in dust by
earthworms and benthic organisms, to characterize the bioavailability
of contaminants of concern in waste dust;
- when concentrations of chemicals of concern have been better characterized,
a further tier of ecological risk assessment is warranted to better
understand the risk to the ecosystem;
- Environment Canada should encourage the development of standards
and guidelines for beryllium and PBDE;
- environmental standards and Best Management Practices should be established
for all facilities, limiting the deposition of water and dust in the
environment.
1 Hierarchy
of Controls is essentially an operational strategy which promotes controlling
the hazard at the source and using the best practices to reducing the
hazard.
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